I would suggest to put all the "service routines" in a module and keep your "main" script to a bare minimum, calling the various subroutines in the module instead.

Note that having global variables is to be limited as much as possible (some purists say to avoid it at all costs) and that spanning your global variables accross files is not a good idea (unless you really know what you are doing and there is no other elegant way to do it). Certainly do not rely on global variables in your main script to be used by the modules' subroutines. Instead pass your data as parameters to your subroutine calls.

There is a very nice new book "Perl Medic" which deals exactly with this type of things.